Vybrané aplikace modelování úpravnických procesů s redukcí abrazivního opotřebení sypkými hmotami pomocí DEM simulací

Abstract

The dissertation thesis presents a comprehensive numerical modelling methodology in an application dealing with abrasive wear processes caused by particulate materials. At the beginning of the dissertation, the abrasive wear caused by particulate materials, its mechanisms and the influences entering the abrasive wear process are described. This is followed by a detailed description of the experimental set-up selected to obtain wear resistance values. The theoretical review also presents the current state of the discrete element method, which is nowadays used in conjunction with the finite element method not only in science and research but also in industry. This dissertation demonstrates the link between real abrasive wear problems in industry and a modern numerical method that allows simulations to optimize the operating conditions, ensure a suitable selection of construction materials and design the right technology. This link fulfilled the objectives of the dissertation. In the practical part of the dissertation, a method of calibrating the behaviour for the numerical computational of discrete elements method using particulate materials with particles smaller than 2.5 millimetres was described in detail. The choice of particulate materials was explained. Experiments and measurements determining the properties of the selected particulate materials and the values of the input parameters for the calibration behaviour simulations were also described. The best sets of input interaction parameters were selected from the performed and evaluated 1,093 calibration simulations of the virtual particulate material behaviour. Furthermore, the calibration of the abrasive wear caused by particulate materials as a function of the material properties of the structural geometries was performed. The abrasive wear resistance experiment according to ASTM G65-00 is also described in this part of the paper. The calibration simulations of abrasive behaviour were calibrated to the results of these experiments. A total of 74 abrasive wear calibration simulations were performed. Abrasive wear calibrations were performed for combinations of virtual particulate materials and selected structural materials. These combinations were used in an industrial study of rail wheel travel on a rail with abrasive silica sand action. This study in collaboration with Bonatrans Group a.s. presented the applicability of DEM in industrial processes. This dissertation thus comprehensively describes the process of creating numerical simulations of discrete elements with the application of abrasive wear by virtual particulate materials. Calibration and experimental methods are explained and described, leading to an understanding of the individual processes, and increasing the reliability of the simulation models. The result is thus the ability to predict abrasive wear rates under given operating conditions, by varying input parameters or by choosing different materials of construction. The prediction associated with the use of discrete element simulations can thus reduce the costs associated with increased abrasive wear in industrial practice. Proper modification and optimization can reduce the amount of material used, human resources, and the number of spare parts, thus preventing shutdowns associated with failures, repairs, and maintenance.